Caulking cartridge with silicone fluid seal



Sept. 8, 1970 J- c. FARMER 3,527,389

CAULKING CARTRIDGE WITH SILICONE FLUID SEAL Filed Oct. 25, 1968 'lgA/I/ SELR'IOHE OIL CGATING WYING AGENT g/ [/l N! fjIJf/Ilf/f/l/I/ff//////////// INVENTOR JAMES C. FARMER WW WA I United States Patent 3,527,389 CAULKING CARTRIDGE WITH SILICONE FLUID SEAL James C. Farmer, Greensboro, N.C., assignor to Dow Chemical Corporation, Midland, Mich., a corporation of Michigan Filed Oct. 25, 1968, Ser. No. 770,630 Int. Cl. G01f 11/06 US. Cl. 222--327 3 Claims ABSTRACT OF THE DISCLOSURE There is described a caulking cartridge comprising a tubular body, a nozzle at one end and a movable plunger designed to slide within the cartridge to eject compound from the nozzle. The improvement resides in the interior position of a coating of silicone oil between plunger and cartridge and the provision of a removable end cap behind the plunger to enclose a quantity of drying agent, such as calcium chloride.

BACKGROUND OF THE INVENTION The present invention relates to improvements in caulking cartridges, particularly cartridges for containing watercurable caulking compounds.

For many years there have been available hand-operated caulking guns for providing sealant beads in building construction and the like. Such guns are adapted to use disposable tubular cartridges which contain the caulking compound or sealing material. A piston operated by a gun applies pressure to a rear portion of the cartridge, forcing the caulking compound out of the nozzle at the front of the cartridge.

Various types of caulking compounds or sealing materials are known for various specific applications and can be packaged in cartridges such as those mentioned above. Recently there have been introduced to the market place a number of sealant compounds designed for caulking use, which compounds remain in freely flowable form until exposure to water vapor in the air. The water vapor reacts with the compound to form a rigid or semirigid sealing material.

When these types of caulking compounds were packaged in conventional caulking cartridges, it was found to be virtually impossible to prevent some air leakage from getting into the cartridge. Since the air naturally contains a certain amount of water vapor, this air leakage resulted in a partial cure of the formerly flowable material into a rigid or semirigid mass.

While very slight amounts of curing can be tolerated in cartridges of this type, leakage around the plunger in the cartridge caused, after a relatively short amount of time, the adherence of the plunger to the inside wall of the tubular cartridge body. This adherence was, of course, caused by cured caulking compound forming a bond between plunger and wall. It was found with certain types of sealants that even with the most air-tight cartridge seals available, a maximum shelf life of four months without adherence of the plunger was all that could be expected. With the plunger securely adhered to the tubular interior of the cartridge, the application of pressure was likely to cause breakage of either the gun or the cartridge, and the cartridge had to be thrown away.

Various types of modifications of cartridge design either failed to eliminate the problem and substantially increase shelf life of the cartridge, or became prohibitively expensive for use in a disposable construction. In normal use, the cartridges are disposed of after a single filling.

SUMMARY OF THE INVENTION It is accordingly an object of the present invention to provide an improved caulking cartridge specifically designed to improve shelf life of water-curable, sealantfilled cartridges. It is the further object to provide a waterproof construction for disposable cartridges which is as economical as is possible to manufacture.

In accordance with these and other objects, there is provided by the present invention a construction in which the improvement resides in (l) forming a tighter seal against water vapor between the plunger and interior of the tubular cartridge body, and (2) to dry, insofar as possible, any air which reaches the vicinity of the plunger.

According to the invention, the problems inherent in the prior art are solved very simply by providing a coating of silicone oil between the plunger and the Wall of the tubular member and by providing a quantity of drying agent, or desiccant, immediately adjacent the plunger by enclosure of the desiccant with the cartridge end cap. The resulting construction is simple to manufacture, extremely efiicient and solves the problems inherent in the prior art.

DESCRIPTION OF THE DRAWING The invention will become more clearly understood by those skilled in the art from a consideration of the following detailed description when read in conjunction with the accompanying drawing wherein:

The sole figure is a cross-sectional view in elevation illustrating the preferred embodiment of a caulking cartridge employing the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawing, there is shown in the sole figure a preferred embodiment of a caulking cartridge utilizing the present invention. The cartridge is made up of a tubular member 1 which may be either metallic, molded plastic or foil-coated cardboard, for example, having an exit nozzle 2 afiixed to one end thereof. The nozzle 2 is conventionally closed at its outlet end by a seal 3. While the body 1, nozzle 2 and seal 3 are shown in the drawing as being integrally molded forming a single piece of material, it is to be understood that any conventional type of cartridge construction can be used for these parts. For example, the nozzle end of the tubular member 1 can be crimped around a nozzle support disc, if desired.

The seal 3 can be designed to be either cut from the nozzle by means of a knife, or the like, or to be simply punctured by a pointed object or designed to rupture upon application of pressure within. These portions of the cartridge are conventional and form no part of the invention as such.

Disposed within the tubular member 1 at the end opposite the nozzle end is a plunger 4 having a generally cylindrical surface conforming to the interior of the tubular member 1. In a filled cartridge, a quantity of caulking compound 5 fills the space between the plunger 4 and the nozzle seal 3. Upon application of pressure to the plunger in a direction toward the nozzle, the plunger is designed to slide toward the nozzle, forcing the caulking compound 4 out through the nozzle 2.

The plunger 4 is coated with a silicone oil, preferably having a viscosity between and 1000 centistokes. Such coating can be applied by dipping the plunger 4 into the silicone oil prior to insertion into the tubular member 1. The object of coating the plunger with the silicone oil is to provide a silicone oil film between the plunger and the inside surface of the tubular member '1. It is, therefore,

3 also possible to provide the silicone oil coating on the interior wall of the tubular member instead of on the plunge to accomplish this same end.

While various silicone oils can be used within the viscosity limitations set forth above, that is between 100 centistokes and 1000 centistokes, a dimethylpolysiloxane fluid is preferred because it is easily obtained and economical. It has been found that silicone oils of viscosities below those set forth above sometimes fail to provide a suflicient coating on the plunger for appreciable increase in shelf life. Silicone oils having viscosities greater than those shown tend to interfere with the operation of the device and are more difiicult to apply.

After filling ,the cartridge with the sealant 5 and placing the plunger 4 within the tubular member 1, a quantity of drying agent, such as calcium chloride, is introduced behind the plunger, and a cap 6 is slideably fitted over the open end of the tubular member 1 to enclose the drying agent between the cap and plunger 4.

While calcium chloride. is preferred as a drying agent, because of its ready availability and for reasons of economy, any other desiccant can be applied in its stead. For example, among others, copper sulfate, zinc chloride,

alumina, Mg(ClO and Ba(ClO are useful in this application. Such desiccants can absorb water from air by either adsorption, absorption or both. The only limitations on suitable desiccants are, of course, those which would react chemically with the end cap, the tubular member or the plunger to cause deterioration. For this reason the construction materials must be considered in the choice of drying agent in any given application.

In operation, the end cap serves to some extent to exclude air from the area immediately adjacent the plunger in the cartridge. Before use, however, the cap is discarded along with the drying agent it contains. Since the end cap must be removed to facilitate operation of the plunger by pressure from the piston of the caulking gun, it is desirable that the cap be easily removed. For this reason and for purposes of economy, generally a slip-fit between the cap and tubular body of the cartridge is desirable. This of necessity allows a small amount of air to leak past the cap and into the vicinity of the plunger.

The provision of a quantity of drying agent, generally in granular or flake form between cap and plunger, serves to draw most of the Water from the air which enters this area. At this point the silicone oil filling the space between the plunger and the cartridge Wall serves to repel any water which may still be in the air by virtue of the hydrophobic nature of the silicone oil. Additionally, since the silicone oil fills or substantially fills any space between the plunger and wall, it forms a physical seal also. Still further, the silicone oil acts as a lubricant to provide ease in sliding the plunger through the cartridge when gun pressure is applied.

It will be realized by those skilled in the art that either the use of desiccant alone or the use of silicone oil alone will result in improved performance over existing cartridges. Preferably, therefore, both are used together, but it should be understood that two features can be used independently. Obviously other modifications and variations will become apparent to those skilled in the art from a consideration of the foregoing. Therefore, it is to be understood that the invention can be practiced other than as specifically described.

That which is claimed is:

1. In a caulking cartridge comprising a tubular body adapted for insertion in a caulking gun, a nozzle for ejection of caulking compound mounted at one end of said body, and a slideable plunger adapted upon application of pressure for sliding from an initial position at one end of said tubular body to the nozzle end substantially in contact with the inner surface of said tubular body to eject said caulking compound from said body, the improvement which comprises:

a removable end cap covering the end of said tubular member which is opposite the end at which said nozzle is attached, and

a quantity of drying agent placed between said end cap and said plunger.

2. In a caulking cartridge comprising a tubular body adapted for insertion in a caulking gun, a nozzle for ejection of caulking compound mounted at one end of said body, and a slideable plunger adapted upon application of pressure for sliding from an initial position at one end of said tubular body to the nozzle end substantially in contact with the inner surface of said tubular body to eject said caulking compound from said body, the improvement which comprises:

a coating of silicone oil interposed between said plunger and said inner surface of said tubular body, said silicone oil consisting of dimethylpolysiloxane of a viscosity between centistokes and 1000 centistokes,

a removable end cap covering the end of said tubular member which is opposite the end at which said nozzle is attached, and

a quantity of drying agent placed between said end cap and said plunger.

3. In a caulking cartridge comprising a tubular body adapted for insertion into a caulking gun, a nozzle for ejection of caulking compound mounted at one end of said body, and a slideable plunger adapted upon application of pressure for sliding from an initial position at one end of said tubular body to the nozzle end substantially in contact with the inner surface of said tubular body to eject said caulking compound from said body, the improvement which comprises:

a coating of silicone oil interposed between said plunger and said inner surface of said tubular body,

a removable end cap covering the end of said tubular member which is opposite the end at which said nozzle is attached, and

a quantity of drying agent placed between said end cap and said plunger.

References Cited UNITED STATES PATENTS 2,343,026 2/1944 Radbruch 222386 2,478,078 8/1949 Battenfeld 222327 3,312,306 4/1967 Carlston 252-ll X STANLEY H. TOLLB ERG, Primary Examiner U.S. PATENT OFFICE UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Pat t 5,527,3 9 Dated; September 8, 197;)

James C. Farmer It is certified that errors appear in the aboveidentifie( patent and that said Letters Patent are hereby corrected as shown below:

In the title: Change the assignor from Dow Chemical Corporation" to read --Dow Corning Corporation--.

smmzn AND .R EALED NW 2 44% (SEAL) EMM-Flewhmhvim-um I. W, JR Attesting Offioer Gamissiom of Patents 

